Pesticides

ABSTRACT

A compound of formula I: ##STR1## in which formula: D represents hydrogen or a cyano group; 
     X represents halogen; 
     A represents an alkyl group (typically a C 1  -C 6  alkyl group); 
     n is 0 to 4; 
     RCOO. represents a residue of an acid RCO 2  H, which acid, or an ester-forming derivative of which acid, on reaction with α-cyano-3-phenoxybenzyl alcohol or an ester-forming derivative thereof, gives rise to an α-cyano-3-phenoxybenzyl ester having pesticidal properties.

This application is a continuation of application Ser. No. 497,409, filed May 23, 1983, now abandoned.

This invention relates to pesticides and in particular to pesticidal compounds, the preparation of such compounds, intermediates for use in their preparation, compositions containing such compounds and the use of such compounds and compositions to control pests, for example pests present in soil.

Accordingly the present invention comprises a compound of formula I ##STR2## in which formula: D represents hydrogen or a cyano group;

X represents halogen;

A represents an alkyl group (typically a C₁ -C₆ alkyl group)

n is 0 to 4;

RCOO. represents a residue of an acid RCO₂ H, which acid, or an ester-forming derivative of which acid, on reaction with α-cyano-3-phenoxybenzyl alcohol or an ester-forming derivative thereof, gives rise to an α-cyano-3-phenoxybenzyl ester having pesticidal properties.

Although the acid residue RCOO may derive from a wide variety of acids as hereinafter described, it is preferred that the acid residue is of a cyclopropane carboxylic acid such as chrysanthemic acid or a 2,2-dimethyl-3-(dihalovinyl)cyclopropane carboxylic acid, the 2,2-dimethyl-3-(dibromovinyl)cyclopropane carboxylic acid, especially when in the (1R,cis) form being of especial interest.

It is generally preferred, moreover, that D represents hydrogen and for the substituent group --CH═CHX to be disposed at the three or four position in the benzene ring with respect to the ester linkage. Compounds in which the hydrogens in the double bond of the substituent group are disposed in the Z configuration (whether or not in the isomerically pure form) are of particular interest, the compound 4(Z-3-chloroallyl)benzyl(1R)cis-3(2,2-dibromovinyl)-2,2-dimethylcyclopropane carboxylate displaying particularly high toxicity. The group A when present typically represents methyl, and compounds in which two alkyl, e.g. methyl, groups are disposed at the 2,6 position in the ring with respect to the ester link are of especial interest.

X preferably represents fluorine, chlorine or bromine, chlorine being particularly preferred.

Esters I may be prepared by reaction of an acid RCO₂ H or an ester-forming derivative thereof with an intermediate of formula II ##STR3## wherein Y represents a hydroxyl or halogen e.g. chlorine.

Intermediates of formula II are also included in a further aspect of the present invention.

Intermediates II in which Y represents --OH may be produced from aldehydes of formula IIA which are also included within the scope of the present invention. ##STR4## In accordance with a further aspect of the present invention, a compound II wherein Y represents OH and D represents hydrogen is produced from a compound IIA by reduction thereof. Such reduction may be hydride reduction using a reagent such as lithium aluminium hydride.

In accordance with a further aspect of the present invention, a compound II wherein Y represents OH and D represents a cyano group is produced from a compound IIA by treatment with an alkali metal cyanide. The reaction is typically conducted under acidic conditions in a homogenous reaction mixture comprising an aqueous organic solvent.

Intermediates II in which Y represents halogen and D represents hydrogen may be produced from intermediates II in which Y represents --OH and D represents hydrogen, in accordance with a further aspect of the present invention by treatment of the latter intermediates with a halogenating reagent of the class employed for conversion of carboxylic acids to acyl halides e.g. SO(hal)₂, typically with pyridine or P(hal)₃, hal representing chlorine or bromine.

Compounds IIA may be produced in accordance with a further aspect of the present invention by reaction of a Grignard reagent of formula IIB ##STR5## wherein P represents bromine or iodine and K represents a ketal group, typically ethylene ketal --OCH₂.CH₂ O-- with a complex formed between a compound Q--CH₂ --CH═CH--X wherein Q represents bromine or chlorine, typically chlorine, and, respectively, cuprous bromide or a mixture of lithium and cuprous chlorides, followed by treatment of the reaction mixture with mild aqueous acid e.g. NH₄ Cl.

Compounds IIA may alternatively be produced in accordance with a further aspect of the present invention by reaction of a compound of formula IIC. ##STR6## with selective hybride reducing agent such as sodium dihydrobis (2-methoxyethoxy)aluminate followed by hydrolysis of the ketal group using for example dilute acid. The latter method for producing compounds IIA is especially suitable when X represents fluorine. Both E and Z isomers of the 3-haloallylbenzaldehyde are generally produced and can be separated by known techniques such a distillation or chromatography e.g. gas chromatography.

Compounds IIC may be produced, in accordance with a further aspect of the present invention by a Wittig reaction of a compound of formula IID with a halocarbon CX₂ W₂ in which W represents a halogen the atomic weight of which is no less than the atomic weight of X, preferably, when X represents fluorine, in the presence of zinc powder. ##STR7##

In the compounds of formula I, R represents the residue of a carboxylic acid RCOOH which is an acid known to be capable of forming pesticidal compounds when esterified with --cyano-3-phenoxybenzyl alcohol. There are a large number of carboxylic acids that are known to form pesticidal compounds of this type and these carboxylic acids fall, for the most part, into two clearly defined groups. The first group is the cyclopropane carboxylic acids which are the compounds where R is a group of the formula: ##STR8## In formula III R³ and R⁴ will normally be an alkyl group, usually the same alkyl group, containing 1 to 4 carbon atoms and, as is well known in the art, dimethyl substitution normally gives high activity.

R² in formula III will normally be hydrogen or an alkyl group containing 1 to 4 carbon atoms and here the experience of the art indicates that R² will usually be hydrogen for maximum activity except in those compounds where R¹ is also an alkyl group, in which case R² preferably is an alkyl group, R¹, R², R³ and R⁴ all conveniently being the same alkyl group, e.g. methyl.

In formula III R¹ can be hydrogen or a substituted or unsubstituted acyclic or carbocyclic group. When R¹ is an unsubstituted hydrocarbyl group, it can be a straight chain or branched saturated or unsaturated acyclic or carbocyclic group such as an alkyl group, an alkenyl or alkadienyl group or a cycloalkyl, cycloalkylalkyl or cycloalkylalkenyl group. These hydrocarbyl groups preferably contain up to 10, particularly up to 6 carbon atoms.

When group R¹ is substituted, it is preferably one of the hydrocarbyl groups mentioned above which is substituted by one or more halogeno groups which may be fluorine, chlorine or bromine or by an alkoxy or oximino group or alkoxycarbonyl group, as in a group R¹ of particular interest of formula --CH═CHCO₂ R_(x) wherein R_(x) represents an alkyl group typically containing 1 to 4 carbon atoms. When the substituents are two or more halogeno substituents, the halogeno substituents need not necessarily be the same halogen while when alkoxy groups are present, these preferably contain up to 4 carbon atoms and will normally be methoxy groups.

One particularly valuable structure for the group R¹ is of formula IV ##STR9## where R⁷ and R⁸, which may be the same or different, are each an alkyl group containing 1 to 4 carbon atoms, a trifluoromethyl group or a halogeno group, which may be the same or different and are preferably fluorine, chlorine or bromine. One of R⁷ and R⁸ may also represent hydrogen or a phenyl or substituted phenyl group. Alternatively, R⁷ and R⁸ may together form a straight or branched substituted or unsubstituted saturated or unsaturated divalent hydrocarbon chain which may be substituted by one or more hetero atoms e.g. O, N or S, so that R⁷ and R⁸ together with the carbon atom to which they are attached form a carbocyclic or heterocyclic ring which will preferably contain 5 to 7 ring atoms, optionally 1 or 2 carbon-to-carbon double bonds and optionally one or more alkyl (C₁ -C₄) or halogeno substituents on the cycloaliphatic ring. Other compounds of interest are those in which R is a group of the structure ##STR10## where the dotted line represents an optional double bond and X₁ represents H or halogen such as chlorine.

Specific cyclopropane carboxylic acids from which the compounds I of the present invention may be structurally derived include the following:

Chrysanthemic acid including particularly (1R)-trans chrysanthemic acid;

Pyrethric acid;

Dimethylcyclopropane carboxylic acid;

Trimethylcyclopropane carboxylic acid;

Tetramethylcyclopropane carboxylic acid;

2,2-Dimethyl-3-(cyclopentylidenemethyl)cyclopropane carboxylic acid;

2,2-Dimethyl-3-(2,2-dibromovinyl)cyclopropane carboxylic acid; particularly the (1R)-cis isomer thereof;

2,2-Dimethyl-3-(2,2-dichlorovinyl)cyclopropane carboxylic acid; particularly the (1R)-cis isomer thereof;

2,2-Dimethyl-3-(1,2,2,2-tetrabromoethyl)cyclopropane carboxylic acid;

2,2-Dimethyl-3-(1,2-dibromo-2,2-dichloroethyl)cyclopropane carboxylic acid;

2,2-Dimethyl-3-(2-chloro-3,3,3-trifluoropropenyl)cyclopropane carboxylic acid;

2,2-Dimethyl-3-(tetrahydro-2-oxo-thien-3-ylidenemethyl)cyclopropane carboxylic acid.

The second major class of carboxylic acids from which the esters of formula I may be structurally derived are the α-substituted aryl acetic acid esters. In these compounds R in formula I will normally be of the structure ##STR11## wherein Ar represents a divalent aryl residue, R⁵ represents a saturated or unsaturated straight chain or branched acyclic or cyclic hydrocarbon residue and R⁶ represents hydrogen or one or more alkyl, alkoxy (including substituted alkoxy such as OCF₃ and OCHF₂) or halogeno substituents.

Ar will normally be an aryl residue based on a benzene ring although other aryl residues, e.g. polynuclear residues are also of interest. R⁵ will normally be a saturated straight or branched chain hydrocarbon group particularly an alkyl group containing up to 8 carbon atoms and it is often desirable that this alkyl group should contain at least one secondary carbon atom particularly when that secondary carbon atom is directly bonded to the carbon atom directly bonded to the R⁶ substituted aryl group. Thus R⁵ is preferably an isopropyl group or a secondary butyl group. R⁵ can also be a cycloaliphatic residue, again preferably containing a secondary carbon atom located immediately adjacent to the carbon atom carrying the R⁶ substituted phenyl group, e.g. R⁵ may be a cyclopropyl group or an alkyl substituted cyclopropyl group. R⁵ can also be a cycloalkylalkyl group.

R⁶ is preferably one or more halogeno or halogen-containing substituents, e.g. F, Cl, Br or OCHF₂ or OCF₃ and, when more than one halogeno or halogen-containing substituent is present, they will normally be but are not necessarily the same halogen. When R⁶ is an alkyl or alkoxy group, these preferably contain up to 4 carbon atoms and again, when more than one such group is present, they need not necessarily be the same groups. When only one substituent R⁶ is present, it is preferably present in the para-position. When more than one R⁶ substituent is present, the para-position is preferably substituted together with one or more of the ortho- and meta-positions.

Another class of carboxylic acids from which the esters of the present invention may be structurally derived are α-substituted arylamino acetic acids of the type ##STR12## where R⁵, R⁶ and aryl are as defined above.

Specific-substituted phenyl acetic acids from which esters of the formula I may be structurally derived include:

α-Isopropyl-p-chlorophenyl acetic acid;

α-Cyclopropyl-p-chlorophenyl acetic acid;

α-Cyclopropyl-p-methylphenyl acetic acid;

α-Isopropyl-p-(difluoromethoxy)-phenyl acetic acid;

α-Isopropyl-(2-chloro-4-trifluoromethyl anilino)acetic acid.

The compounds of the invention exhibit optical isomerism in that the carbon atom bearing the substituent D can exist in the R or S configuration and the present invention includes compounds in which the configuration is substantially completely R or in which the configuration is substantially completely S or mixtures thereof.

Compounds of the invention in which R represents a substituted cyclopropane residue of formula III can exist in the form of both geometrical and optical isomers. This is because of the unsymmetrical substitution at C₁ and C₃ of the cyclopropane ring. Compounds of the present invention include those isomers in which the hydrogen atoms at C₁ and C₃ of the cyclopropane ring are substantially completely in the cis configuration or substantially completely in the trans configuration or mixture thereof. The present invention also includes compounds in which the configuration at C₁ is substantially completely R or substantially completely S and mixtures thereof. In the compounds of the invention in which R represents a group of formula III, the optical configuration at C₁ and C₃ cannot vary independently of the geometrical configuration of the hydrogen atoms at C₁ and C₃ of the cyclopropane ring. The effect of this is that the configuration of the cyclopropane ring can be defined uniquely by specifying the optical configuration at C₁ and the geometrical configuration of the hydrogen atoms at C₁ and C₃ and, for definition purposes, we have adopted nomenclature of the form (1R)-cis, (1R)-trans etc. it being unnecessary to specify the optical configuration at C₃ which is fixed once the other two variables are defined. Adopting this nomenclature avoids the confusion which can arise by having to designate either R or S to the same optical configuration at C₃ depending upon the nature of the substituents on the cyclopropane ring and even those on the side chain.

When R is a group of formula III in which R¹ is a group of formula IV in which the substitution about the ethylenic bond is asymmetrical, that is to say R⁷ ≠R⁸ then the configuration of this part of the molecule can be substantially completely in the E form or substantially completely in the Z form or a mixture thereof.

When R is a group of formula V, the carbon atom to which R⁵ is bonded can exist substantially completely in the S configuration or substantially completely in the R configuration or can be a mixture of the two forms.

The compounds of the present invention can be in the form of single isomers but, having regard to the fact that the compounds have at least one and frequently more than one centre of asymmetry, the compounds of the invention will normally be in the form of isomer mixtures although these isomer mixtures can be optically active and/or substantially completely in one geometric form.

The compounds of the present invention can be prepared by an esterification involving the reaction of an alcohol of formula II or an esterifiable derivative thereof with a carboxylic acid of formula RCOOH or an esterifiable derivative thereof. It is usually convenient in practice to react an alcohol of formula II with an acyl chloride of formula RCOCl or to react a salt of the carboxylic acid, e.g. a silver or triethylammonium salt with a benzylhalide derivative, that is to say a monohaloalkylbenzyl or cyanobenzyl halide which may be ring alkylated or to esterify the carboxylic acid with the alcohol in the presence of dicyclohexyl carbodi-imide and a catalyst.

Alternatively, the esters of the invention can be prepared by transesterification by reacting a C₁ -C₆ alkyl ester of the carboxylic acid with a benzyl alcohol of formula II in the presence of a basic transesterification catalyst. This method is not usually satisfactory where the molecule contains another base-sensitive residue, e.g. where the carboxylic acid is pyrethric acid.

One or more of the pesticidal esters of formula I can be formulated with an inert carrier or diluent to give pesticidal compositions and such compositions form a further aspect of the present invention. These compositions can be in the form of dusts and granular solids, wettable powders, mosquito coils and other solid preparations, or as emulsions, emulsifiable concentrates, sprays and aerosols and other liquid preparations after the addition of the appropriate solvents, diluents and surface-active agents.

Compositions formulated in a manner suitable for controlling soil pests typically by treatment of the soil are of especial interest. For this purpose compositions containing compound I hereinbefore described are particularly suitable as they generally have lower molecular weights than many previously described pyrethroids, and it is envisaged that their relatively high vapour pressures allow them to diffuse through the soil.

The pesticidal compositions of the invention will normally contain from 0.001 to 25% by weight of the compound of formula I but the compositions can contain higher concentrations of active ingredient of formula I e.g. up to 95% for compositions to be sold as concentrates for dilution before use by the ultimate user.

The compositions of the invention can include diluents such as hydrocarbon oils, e.g. xylene or other petroleum fractions, water, anionic, cationic or non-ionic surface-active agents, anti-oxidants and other stabilisers as well as perfumes and colouring matters. These inert ingredients may be of the type and in proportions such as are conventionally used in pesticidal compositions containing pyrethroid-like compounds.

In addition to these inactive ingredients, the compositions of the present invention may contain one or more further active ingredients which may be other pesticidal compounds of the pyrethroid type or of other types and the composition may also include synergists of the type known to be capable of synergising the activity of natural pyrethrin and pyrethroid-like insecticides. Synergists of this type include piperonyl butoxide, tropital and sesamex.

The compounds of formula I can be used to control pest infestation in the domestic, horticultural or agricultural or medical, including veterinary, areas. The compounds or compositions of the invention can be used to combat pest infestation by treating pests or surfaces or environments susceptible to pest infestation with effective amounts of the active compounds of formula I or of compositions containing them. For example, they may be used in a domestic environment for spraying rooms to combat infestation with houseflies or other insects, they can be used for treatment of stored dry crops or cereals to combat infestation by insects or other pests, they can be used to spray growing crops, e.g. cotton or rice to combat infestation by common pests and they can be used in a medical or veterinary field, e.g. as a cattle spray to prevent or treat infestation by insects or other pests.

Although, as hereinbefore indicated, they are of particular interest for the disinfestation of soil to control pests such as the onionfly, Delia antiqua, the compounds may also find application in the control of virus acquisition by and/or transmission in plants particularly when mediated by aphids such as Myzus persicae, the peach-potato aphid.

The compounds are additionally of interest for the control of the pests such as the following:

from the class of the Isopoda, for example Oniscus asellus, Armadillidium vulgare and Porcellio scaber;

from the class of the Diplopoda, for example Blaniulus guttulatus;

from the class of the Chilopoda, for example Geophilus carpophagus and Scutigera spec.;

from the class of the Symphyla, for example Scutigerella immaculata;

from the order of the Thysanura, for example Lepisma saccharina;

from the order of the Collembola, for example Onychiurus armatus;

from the order of the Orthoptera, for example Blatta orientalis, Periplaneta americana, Leucophaea madarae, Blattela germanica, Acheta domesticus, Gryllotalpa spp., Locusta migratoria migratorioides, Melanoplus differentialis and Schistocerca gregaria;

from the order of the Dermaptera, for example Forficula auricularia;

from the order of the Isoptera, for example Reticulitermes spp;

from the order of the Anoplura, for example Phylloxera vastatrix, Pemphigus spp., Pediculus humanus corporis, Haematopinus spp. and Linognathus spp.;

from the order of the Mallophaga, for example Trichodectes spp. and Demalinea spp.;

from the order of the Thysanoptera, for example Hercinothrips femoralis and Thrips tabaci;

from the order of the Heteroptera, for example Eurygaster spp., Dysdercus intermedius, Piesma quadrata, Cimex lectularius, Rhodnius prolius and Triatoma spp.;

from the order of the Homoptera, for example Aleurodes brassicae, Bemisia tabaci, Trialeurodes vaporariorum, Aphis gossypii, Brevicoryne brassicae, Cryptomyzus ribis, Doralis fabae, Doralis pomi, Eriosoma lanigerum, Hyalopterus arundinis, Macrosiphum avenae, Myzus spp., Phorodon humuli, Rhopalosiphum padi, Empoasca spp., Euscelis bilobatus, Nephotettix cincticeps, Lecanium corni, Saissetia oleae, Laodelphax striatellus, Nilaparvata lugens, Aondiiella aurantii, Aspidiotus hederae, Pseudococcus spp. and Psylla spp.;

from the order of the Lepidoptera, for example Pectinophora gossypiella, Bupalus piniarius, Cheimatobia brumata, Lithocolletis blancardella, Hyponomeuta padella, Plutella maculipennis, Malacosoma neustria, Euproctis chrysorrhoea, Lymantria spp., Bucculatrix thurberiella, Phyllocnistis citrella, Agrotis spp., Euxoa spp., Feltia spp., Earias insulana, Heliothis spp., Laphygma exigua, Mamestra brassicae, Panolis flammea, Prodenia litura, Spodoptera spp., Trichoplusia ni, Carpocapsa pomonella, Pieris spp., Chilo spp., Pyrausta nubilalis, Ephestia kuehniella, Galleria mellonella, Cacoecia podana, Capua reticulana, Choristoneura fumiferana, Clysia ambiguella, Homona magnanima and Tortrix viridana;

from the order of the Coleoptera, for example Anobium punctatum, Rhizopertha dominica, Bruchidius obtectus, Acanthoscelides obtectus, Hylotrupes bajulus, Agelastica alni, Leptinotarsa decemlineata, Phaedon cochleariae, Diabrotica spp., Psylliodes chrysocephala, Epilachna varivestis, Atomaria spp., Oryzaephilus surinamensis, Anthonomus spp., Sitophilus spp., Otiorrhynchus sulcatus, Cosmopolites sordidus, Ceuthorrhynchus assimilis, Hypera postica, Dermestes spp., Trogoderma spp., Anthrenus spp., Attagenus spp., Lyctus spp., Meligethes aeneus, Ptinus spp., Niptus hololeucus, Gibbium psylloides, Tribolium spp., Tenebrio molitor, Agriotes spp., Conoderus spp., Melolontha melolntha, Amphimallon solstitialis and Costelytra zealandica;

from the order of the Hymenoptera, for example Diprion spp., Hoplacampa spp., Lasius spp., Monomorium pharaonis and Vespa spp.,

from the order of the Diptera, for example Aedes spp., Anopheles spp., Culex spp., Drosophila melanogaster, Musca spp., Fannia spp., Calliphora erythrocephala, Lucilia spp., Chrysomyia spp., Cuterebra spp., Gastrophilus spp., Hyppobosca spp., Stomoxys spp., Oestrus spp., Hypoderma spp., Tabanus spp., Tannia spp., Bibio hortulanus, Oscinella frit, Phorbia spp., Pegomyia hyoscyami, Ceratitis capitata, Dacus oleae and Tipula paludosa;

from the order of the Siphonaptera, for example Xenopsylla cheopis and Ceratophyllus spp.;

from the class of the Arachnida, for example Scorpio maurus and Latrodectus mactans;

from the order of the Acarina, for example Acarus siro, Argas spp., Ornithodoros spp., Dermanyssus gallinae, Eriophyes ribis, Phyllocoptruta oleivora, Boophilus spp., Rhipicephalus spp., Amblyomma spp., Hyalomma spp., Ixodes spp., Psoroptes spp., Chorioptes spp., Sarcoptes spp., Tarsonemus spp., Bryobia praetiosa, Panonychus spp. and Tetranychus spp.

The invention is illustrated by the following Examples.

Temperatures are in °C.

EXAMPLE 1 4(Z-3-chloroallyl)benzaldehyde

Dry Mg (1.15 g) under dry N₂ in a flask is covered with THF (10 ml) and a crystal of I₂ added. 5 ml of a solution of 4-bromobenzaldehyde ethylene acetal (10.0 g) in THF (40 ml) is added and kept until it becomes warm, when it is cooled to 15°, and the remainder of the acetal added over 15 minutes, then stirred for an additional 1 hour. A mixture of ground lithium chloride (0.35 g) and copper (I) chloride (0.70 g) dissolved in THF is prepared, treated with Z-1,3-dichloropropene (8.0 g) produced by spinning band distillation of commercially available 1,3-dichloropropene comprising a mixture of the E and Z isomers and cooled to -20°. The above Grignard solution (under moisture excluding conditions) is then added to this solution during 5 minutes, and allowed to warm to 20° with stirring for 16 hours. Saturated aqueous ammonium chloride is added and the organic layer evaporated under reduced pressure to a small residue, which is dissolved in THF (100 ml), cooled to -10°, treated with 3N HCl (50 ml), then stirred at 20° for 1 hour. The product is partitioned between ether and water, and the ether layer washed with saturated aqueous NaHCO₃, H₂ O, saturated aqueous NaCl, dried (MgSO₄) and the residue chromatographed on florisil. The fraction eluted by 15 % diethyl ether in petroleum ether bp 60°-80° C. is collected and purified by preparative HPLC. Yield 1.12 g (14%) n_(D) ²⁰ 1.5655.

EXAMPLE 2 4(Z-3-chloroallyl)benzyl alcohol

The aldehyde (0.22 g) of Example 1 in ether (5 ml) is added to lithium aluminum hydride (0.08 g) in ether (5 ml), and the mixture stirred at 20° for 1 hour. After successive dropwise additions of water (80 l), 15% NaOH (80 l) and water (240 l), the resulting clear ether layer (+ washings) is evaporated to a residue of 4(Z-3-chloroallyl)benzyl alcohol yield 0.19 g (86%) n_(D) ²⁵ 1.5529.

EXAMPLE 3 4(Z-3-chloroallyl)benzyl(1R)cis-3(2,2-dibromovinyl)-2,2-dimethylcyclopropane carboxylate

To a solution of (1R)cis 3(2,2-dibromovinyl)-2,2-dimethylcyclopropane carboxylate (0.11 g) in CH₂ Cl₂ (3 ml) cooled to 0° is added successively 4(Z-3-chloroallyl)benzyl alcohol (0.070 g) in CH₂ Cl₂ (2 ml), N,N¹ dicyclohexylcarbodiimide (0.076 g) in CH₂ Cl₂ (2 ml), and 4-dimethylamino pyridine (0.010 g). This mixture is stirred for 30 minutes at 0°, then for 16 hours at 20°. The resulting precipitate is filtered off, the filtrate evaporated under reduced pressure and the residue chromatographed on florisil. The fraction eluted by 7% diethyl ether in petroleum ether bp 60°-80° C. ether in petrol is evaporated to a residue of 4(-3-chloroallyl)benzyl (1R)cis-3(2,2-dibromovinyl)-2,2-dimethylcyclopropane carboxylate (0.15 g) 91% n_(D) ²⁰ 1.5684.

EXAMPLES 4-7E

Aldehydes of formula IIA are generally prepared by following the method described in Example 1, yield and refractive index being given in Table 1.

3- and 4-(3-bromoallyl)benzaldehyde are prepared as described in Example 1 respectively from 3- and 4-bromobenzaldehyde but using a mixture of E and Z isomers of 1,3-dibromopropene and cuprous bromide in place of the mixture of lithium chloride and cuprous chloride. The resultant aldehyde is separated into E and Z isomers by HPLC on silica eluted with 4% diethyl ether in petroleum ether, bp 60°-80° C.

2,6-dimethyl-4-bromobenzaldehyde ethylene acetal for conversion to 2,6-dimethyl-4-(Z-3-chloroallyl)benzaldehyde is prepared by an adaptation of the method described in Organic Synthesis, Volume V p.139, for the preparation of 2-bromo-4-methylbenzaldehyde as follows:

A. Formaldoxime

A mixture of paraformaldehyde (11.5 g, 0.383 mole) and hydroxylamine HCl (26.2 g, 0.377 mole) are heated in water (160 ml) until a clear solution is obtained (ca 10 minutes at 80° C.). Hydrated sodium acetate (50.8 g) is added, and the mixture is refluxed for 15 minutes giving a 10% aqueous solution of formaldoxime.

B. Diazonium salt

Concentrated HCl (56.4 ml) is added slowly with cooling (15° C.), to a mixture of bromoxylidine (50.0 g, 0.25 mole) and water (80 ml). The purple suspension turns into a grey suspension and more water (80 ml) is added. The mixture is then cooled in ice/salt to below 5° C. Sodium nitrite (17.5 g, 0.254 mole) in water (40 ml) is added dropwise, keeping the temperature below 5° C. Stirring is continued for 15 minutes, to give an orange solution and some purple suspension. The solution is made neutral by addition of NaOAc (21.9 g) in water (40 ml). The mixture is filtered through a coarse sinter and kept cold.

C. Aldehyde

Hydrated copper sulphate (6.5 g) is dissolved in water and mixed with the aqueous formaldoxime, Na₂ SO₃ (1.0 g) and aqueous solution of sodium acetate (160 g in 170 ml). This mixture is maintained at ca. 10° with an ice/water bath and stirred vigorously. The aqueous diazonium solution is added in portions via a funnel, effervescence occurring. Stirring is continued overnight. Concentrated HCl (250 ml) is added in the morning and the mixture is refluxed for 90 minutes, then steam distilled, 2000 ml of distillate being collected. This is extracted with ether (2×200 ml), washed with saturated aqueous NaHCO₃, H₂ O, saturated aqueous NaCl, dried over MgSO₄ to give 34.2 g of an orange liquid which solidifies on cooling.

This residue is added with cooling to a 40% aqueous solution of sodium metabisulphite (50 g+75 ml H₂ O). This is stirred overnight, the cream precipitate becoming thicker. The precipitate is filtered, washed with water, then ether. The precipitate is suspended in water and concentrated H₂ SO₄ added with cooling. The mixture is refluxed gently for 90 minutes, cooled, extracted with ether the etheral extracts are treated with saturated aqueous NaHCO₃, H₂ O, saturated aqueous NaCl and dried over MgSO₄ and the solvent is removed to give 13.34 g aldehyde (25%) as white needles.

D. Acetal

A mixture of aldehyde (30.7 g), ethylene/glycol (8.94 g), p-toluenesulphonic acid (0.4 g) and benzene (150 ml) is refluxed in a Dean and Stark apparatus overnight, and 2.6 ml H₂ O is collected. The mixture is cooled and stirred with K₂ CO₃ for 30 minutes, filtered and the K₂ CO₃ washed with ether and solvent removed. The solid residue is distilled (mp ca 100°) in vacuo to yield the product, bpt 108°-118° (0.05 mm Hg), 34.33 g (93%).

3- and 4-(3-fluoroallyl)benzaldehyde are prepared by the following method for 3-(3-fluorallyl)benzaldehyde:

A. 3-(Formylmethyl)benzaldehydeethylene ketal

3-Allylbenzaldehydeethylene ketal (2.0 g, prepared using Cu(I)Br only and allyl bromide by the method of Example 1 from 3-bromobenzaldehydeethylene ketal but omitting hydrolysis with 3N HCl) in dichloromethane (70 ml) at -78° is subjected to a stream of ozone until a slight excess has been introduced (15 minutes). Whilst still cold acetic acid (15 ml), water (1.5 ml) and zinc (10 g) are added to the mixture which is allowed to warm to -5° C. After filtering through Celite, the mixture is diluted with water, extracted with dichloromethane, and the extract washed (saturated sodium bicarbonate) and dried. Distillation gives the product (1.6 g), b.p. 58°-65°/0.1 mm Hg, n_(D) ²⁰ 15304.

B. 3(3,3-Difluoroallyl)benzaldehydeethylene ketal

A solution of triphenylphosphine (6.0 g) in dimethyl acetamide (10 ml) is added under nitrogen to a stirred mixture of dibromodifluoromethane (4.8 g), and the aldehyde from a (1.5 g) in dimethylacetamide (15 ml) at 0° during 15 minutes. After 30 minutes at 20°, zinc dust (0.5 g) is added in small portions, and the mixture is then warmed to 100° for 1 hour. After cooling the mixture is filtered, shaken with water and extracted three times with ether. The extract material is chromatographed on florisil to yield the product (0.9 g), n_(D) ²⁰ 1.5172, after a fraction consisting predominantly of triphenylphosphine.

C. 3(3-Fluoroallyl)benzaldehyde

The difluoroketal (0.5 g) from B and sodium dihydro-bis(2-methoxyethoxy)aluminate (1 g of a 70% solution in toluene) in toluene (10 ml) are heated to 110° for 7 hours, then cooled. The reaction mixture is stirred with 3N HCl (30 ml) at 20° for 2 hours, then the organic layer (combined with an ether extract of the aqueous layer) is washed, dried and evaporated to yield the product (0.32 g), n_(D) ²⁰ 1.5440, shown by 'H NMR to be a mixture of E and Z isomers.

                  TABLE I                                                          ______________________________________                                         Aldehydes of formula IIA                                                                                                  refrac-                                                       Configura-       tive                                Ex.             Position of                                                                              tion in     yield                                                                               index                               No.  ( .sub.--A).sub.n                                                                         side chain                                                                               side chain                                                                              .sub.--X                                                                          (%)  (n .sub.D.sup.20)                   ______________________________________                                         4    H          4         E       Cl  8    1.5671                              5    H          3         Z       Cl  8    1.5621                              6    H          3         E       Cl  7    1.5660                              7    2,6-dimethyl                                                                              4         Z       Cl  11   1.5663                              .sup. 7A                                                                            H          3         E       Br  4    1.5866                              .sup. 7B                                                                            H          3         Z       Br  2    1.5820                              .sup. 7C                                                                            H          4         E (80%) Br  3    1.5861                                                         +                                                                             Z (20%)                                               7D  H          4         Z (90%) Br  7    1.5830                                                        +                                                                              E (10%)                                              .sup. 7E                                                                            H          3         E + Z   F   36   1.5440                              ______________________________________                                    

EXAMPLES 8-11

Alcohols of formula II are prepared by following the method described in Example 2, the yield and refractive index being given in Table II.

                  TABLE II                                                         ______________________________________                                         Alcohols of formula II (D = H)                                                                                            refrac-                                                     Configura-         tive                                Ex.           Position of                                                                              tion in       yield                                                                               index                               No.  ( .sub.--A).sub.n                                                                       side chain                                                                               side chain                                                                                .sub.--X                                                                          (%)  (n .sub.D.sup.20)                   ______________________________________                                          8   H        4         E         Cl  93   1.5567                               9   H        3         Z         Cl  98   1.5561                              10   H        3         E         Cl  96   1.5578                              11   2,6-     4         Z         Cl  75   1.5584                                   dimethyl                                                                  .sup. 11A                                                                           H        3         E         Br  95   1.5767                              .sup. 11B                                                                           H        3         Z         Br  82   1.5738                              .sup. 11C                                                                           H        4         E (80%)   Br  100  1.5709                                                      +                                                                              Z (20%)                                                 11D H        4         Z (90%)   Br  100  1.5729                                                      +                                                                              E (10%)                                                .sup. 11E                                                                           H        3         E+ Z (ca. 5:1)                                                                           F   70   1.5316                              ______________________________________                                    

EXAMPLE 12 4-(Z-3-chloroallyl)benzaldehyde cyanohydrin

The aldehyde of Example 1 (0.3 g) and potassium cyanide (0.5 g) in water (1.4 ml) and THF (5 ml) are treated with 40% sulphuric acid (1.5 ml) with cooling to 3° to 8°. After 1 hour at 20°, water is added and the reaction mixture is extracted with ether. The extracts are washed with water and saturated NaCl, dried over MgSO₄ and then evaporated to a residue of α-cyano-4-(Z-3-chloroallyl)benzyl alcohol (0.33 g, 96%) n_(D) ²⁰ 1.5549.

EXAMPLES 13-15

Cyanohydrins of formula II are prepared by following the method described in Example 12, the yield and refractive index being given in Table III.

                  TABLE III                                                        ______________________________________                                                                                     refrac-                                                       Configura-       tive                               Ex.                Position of                                                                            ation in    yield                                                                               index                              No.  ( .sub.--A).sub.n                                                                      --D   side chain                                                                             side chain                                                                              .sub.--X                                                                          (%)  (n .sub.D.sup.20)                  ______________________________________                                         13   H      CN     4       E       Cl  98   1.5505                             14   H      CN     3       Z       Cl  98   1.5454                             15   H      CN     3       E       Cl  78   1.5408                             ______________________________________                                    

EXAMPLES 16-46

Esters of formula I are prepared by following the method described in Example 3, or the following method for the production of the compound 4(Z-3-chloroallyl)-2,6-dimethylbenzyl (1R)cis-3-(2,2-dibromovinyl)2,2-dimethylcyclopropane carboxylate of Example 28, the yield and refractive index being given in Table IV:

4(Z-3-chloroallyl)-2,6-dimethylbenzyl(1R)cis-3-(2,2-dibromovinyl)2,2 dimethylcyclopropane carboxylate

The alcohol of Example 11 (0.088 g) in benzene (2 ml) is added to (1R)cis 3-(2,2-dibromovinyl) 2,2-dimethyl cyclopropanecarbonyl chloride (0.134 g) in benzene (3 ml). Pyridine (0.06 ml) is then added and the mixture stired at 20° for 16 hours. This is chromatographed on florisil and the fraction eluted by 7% ether in petrol evaporated to a residue of the title compound (0.15 g, 73%) n_(D) ²⁰ 1.5624.

The pesticidal activity is assessed against houseflies and mustard beetles by using the following techniques:

Houseflies (Musca domestica)

Female flies are treated on the thorax with a one microliter drop of insecticide dissolved in acetone. Two replicates of 15 flies are used at each dose rate and 6 dose rates are used per compound under test. After treatment, the flies are maintained at a temperature of 20°±1° and kill is assessed 24 and 48 hours after treatment. LD₅₀ values are calculated in micrograms of insecticide per fly and relative toxicities are calculated from the inserve ratios of the LD₅₀ values (see Sawicki et al, Bulletin of the World Health Organisation, 35, 893, (1966) and Sawicki et al, Entomologia and Exp. Appli. 10 253, (1967)).

Mustard Beetles (Phaedon cochleariae Fab)

Acetone solutions of the test compound are applied ventrally to adult mustard beetles using a micro drop applicator. The treated insects are maintained for 48 hours after which time kill is assessed. Two replicates of 40 to 50 mustard beetles are used at each dose level and 5 dose levels are used for each compound. Again, LD₅₀ values are calculated and relative potencies are calculated from the inverse ratios of LD₅₀ (see Elliott et al, J. Sci. Food Agric. 20, 561, (1969)).

Relative potencies are calculated by comparison with 5-benzyl-3-furylmethyl (1R)-trans-chrysanthemate (Bioresmethrin) which is one of the more toxic chrysanthemate esters known to house flies and mustard beetles, its toxicity being about 24 times that of allethrin to houseflies and 65 times that of allethrin to mustard beetles.

                                      TABLE IV                                     __________________________________________________________________________     Esters of Formula I                                                            Acid residue RCOO-:                                                                             A1 = (1R)-trans chrysanthemyl                                                  A2 = (1R)-cis-3-(2,2-dibromovinyl)-2,2-dimethylcyclopropa                      ne carboxyl                                                                    A3 = (1RS)-trans-3-(2,2-dichlorovinyl)-2,2-dimethylcyclop                      ropane carboxyl                                                                A4 = (1RS)-cis-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopro                      pane carboxyl                                                                  A5 = (RS)-2,(4-chlorophenyl)-3-methylbutyrate                                  A6 = 2,2,3,3-tetramethylcyclopropane carboxylate              Relative Potency to Houseflies and Mustard Beetles (Bioresmethrin = 100)       given under HF and MB respectively                                             Example   Acid     Position of                                                                          Configuration                                                                            Yield                                                                              Refractive                                                                           Relative potency                  No.  (A).sub.n                                                                           residue                                                                              D  side chain                                                                           in side chain                                                                         X  (%) index (n.sub.D.sup.20)                                                               HF  MB                            __________________________________________________________________________      3   H    A2    H  4     Z      Cl 91  1.5684                                                                               380 15                            16   H    A1    H  4     Z      Cl 36  1.5303                                                                               46  9                             17   H    A3    H  4     Z      Cl 89  1.5454                                                                               57  25                            18   H    A4    H  4     Z      Cl 63  1.5468                                                                               93  7.6                           19   H    A5    H  4     Z      Cl 85  1.5504                                                                               7.5 1.4                           20   H    A6    H  4     Z      Cl 62  1.5202                                                                               77  1.8                           21   H    A1    H  4     E      Cl 65  1.5317                                                                               6.2 0.8                           22   H    A2    H  4     E      Cl 98  1.5713                                                                               93  6.1                           23   H    A1    H  3     Z      Cl 82  1.5255                                                                               5.1 3.0                           24   H    A2    H  3     Z      Cl 80  1.5650                                                                               74  14                            25   H    A1    H  3     E      Cl 70  1.5280                                                                               5   1.5                           26   H    A2    H  3     E      Cl 95  1.5610                                                                               15  11                            27   2,6  A1    H  4     Z      Cl 58  1.5331                                                                               7.3 6.3                                dimethyl                                                                  28   2,6  A2    H  4     Z      Cl 73  1.5624                                                                               53  57                                 dimethyl                                                                  28A  2,6  A3(60%)                                                                              H  4     Z      Cl 100 1.5448                                                                               1.7 15                                 dimethyl                                                                            +A4(40%)                                                             28B  2,6  A6    H  4     Z      Cl 94  1.5230                                                                               11.5                                                                               1.2                                dimethyl                                                                  29   H    A1    CN 4     Z      Cl 76  1.5294                                                                               ca 0.4                                                                             ca 0.1                        30   H    A2    CN 4     Z      Cl 81  1.5680                                                                               5.2 1.9                           31   H    A1    CN 4     E      Cl 77  1.5270                                                                               0.2 non-toxic                     32   H    A2    CN 4     E      Cl 73  1.5480                                                                               2.8 0.4                           33   H    A1    CN 3     Z      Cl 32  1.5274                                                                               28  13                            34   H    A2    CN 3     Z      Cl 70  1.5621                                                                               11  59                            35   H    A1    CN 3     E      Cl 71  1.5303                                                                               1.3 7.7                           36   H    A2    CN 3     E      Cl 61  1.5475                                                                               8.9 16                            37   H    A1    H  4     E +  Z(4:1)                                                                           Br 70  1.5381                                                                               3.2 0.75                          38   H    A2    H  4     E + Z(4:1)                                                                            Br 98  1.5790                                                                               32  4.6                           39   H    A1    H  4     Z + E(9:1)                                                                            Br 79  1.5361                                                                               10.5                                                                               3.8                           40   H    A2    H  4     Z + E(9:1)                                                                            Br 73  1.5758                                                                               235 4.6                           41   H    A1    H  3     Z      Br 64  1.5392                                                                               3.2 0.8                           42   H    A2    H  3     Z      Br 80  1.5809                                                                               35  7.2                           43   H    A1    H  3     E      Br 71  1.5376                                                                               2.3 non-toxic                     44   H    A2    H  3     E      Br 60  1.5798                                                                               10  5                             45   H    A1    H  3     E + Z  F  41  1.5143                                                                               --  --                            46   H    A2    H  3     E + Z  F  51  1.5542                                                                               --  --                            __________________________________________________________________________ 

We claim:
 1. A compound of the general formula: ##STR13## wherein X represents halogen and the CH₂ CH═CHX group is in the 3- or 4-position on the ring with respect to the RCOOCH₂ -- group and wherein R is a group of the formula: ##STR14## where X is CH₃ or halogen or ##STR15## or ##STR16##
 2. A compound according to claim 1, in which X represents bromine, chlorine or fluorine.
 3. A compound according to claim 1, in which the configuration of hydrogen about the double bond in the substitutent --CH₂ CH═CHX is wholly or predominantly Z.
 4. A compound according to claim 1, in which the substituent --CH₂ CH═CHX is disposed at the four position in the aromatic ring with respect to the ester linkage.
 5. A compound according to claim 1, in which the R is 2,2-dimethyl-3-dihalovinylcyclopropane.
 6. A compound according to claim 1, in which RCOO. represents 2,(4-chlorophenyl)-3-methylbutyroxy.
 7. The compound according to claim 1 which is 4(Z-3-chloroallyl)benzyl-(1R)cis-3(2,2-dibromovinyl)-2,2-dimethylcyclopropane carboxylate.
 8. A compound according to claim 1 wherein Y is Cl or Y is Br.
 9. 4(Z-3-chloroallyl)benzyl-3(2,2-dibromovinyl)-2,2-dimethylcyclopropane carboxylate; 4(Z-3-bromoallyl)benzyl-3(2,2-dibromovinyl)-2,2-dimethylcyclopropanecarboxylate; 4(Z-3-chloroallyl)benzyl-3(2,2-dichlorovinyl)-2,2-dimethylcyclopropane carboxylate; 4(Z-3-chloroallyl)benzylchrysanthemate; 4(Z-3-chloroallyl)-2,6-dimethylbenzyl-3(2,2-dibromovinyl)-2,2-dimethylcyclopropane carboxylate.
 10. An insecticidal composition comprising:(a) an insecticidally effective amount of a compound according to claim 1; and (b) an inert carrier or diluent.
 11. A method of reducing or preventing insect infestation which comprises applying to an insect or to a surface or an environment susceptible to insect infestation an insecticidally effective amount of a compound according to claim
 1. 12. A method according to claim 11, in which the treatment is carried out in soil.
 13. A method according to claim 11, in which the pest which is controlled is an aphid. 